Vacuum X-Ray Diffractometer for High Temperature Studies of Metals Sensitive to Contamination by Oxygen and Nitrogen

An x-ray diffractometer operating in vacuum has been designed and constructed to study metals sensitive to oxygen and nitrogen contamination at elevated temperature. The instrument operates in a vacuum of 2×10−6 mm Hg in which the partial pressure of oxygen and nitrogen is several orders of magnitude lower than the total pressure. The specimen is heated by radiation from a resistance-type furnace to 1200°C. With this instrument it is possible to obtain lattice parameters which are accurate to one part in forty thousand. The thermal expansion of titanium has been investigated up to 650°C. Between room temperature and 400°C the expansion coefficients in directions perpendicular and parallel to the c axis are 9.41×10−6 and 11.18×10−6/°C, respectively. For a random polycrystalline sample, the mean expansion coefficient is 10.0×10−6/°C.